Reversing sensor

Grumblewagon

I discovered that my van has had a "Parking Dynamics" reversing sensor fitted.  Fitted very untidily, I might add with wiring like "a plate of  spaghetti".  Its function is also fairly useless too.  It does detect objects within about 3ft., but if the object
moves away, it won't detect it  again until you shift out of reverse.

Have you any recommendations for a reliable  reversing sensor ?